Planisphere is an astronomy application that lets you use pinch and finger gestures to manipulate a map of the sky. As you zoom in finer detail comes into view. You can double tap on objects to get more information. You can use the compass and accelerometer to show the sky in the direction the phone is being held for the selected time.
Planisphere shows all 88 constellations and their boundaries, 9096 naked eye stars, the Messier deep sky catalogue, the Sun, Moon, planets and the now dwarf planet Pluto. These can be searched and then displayed if above the horizon for the selected time. Rise and setting times are available for all named objects.
The date, time and location can be changed. With GPS you can find your location or you can click on a world map or select a city. There is also a realtime mode that will update to the current time. You can also set a Night Light' which gives the map a red tint for nighttime viewing.
Moon, Mercury, Mars, Venus, Jupiter and Saturn atlases are also available on the App Store.